Light-emitting element, light-emitting device, and electric appliance

The present invention has a layer containing a luminescent substance between the anode and the cathode, and by applying an electric field. The present invention relates to a layer structure of a light emitting element capable of emitting light.

As an example of a photoelectronic device using an organic semiconductor material as a functional organic material These include light emitting elements and solar cells, which are the electrical properties of organic semiconductor materials (carrier transport). It is a device that makes use of physical characteristics (light absorption or light emission), and above all, a light emitting element. It is showing remarkable development.

A light emitting element is formed by sandwiching a layer containing a light emitting substance between a pair of electrodes (anode and cathode), and the light emitting device thereof. The structure consists of holes injected from the anode when a voltage is applied between both electrodes and injection from the cathode. The generated electrons recombine at the luminescent center in the layer containing the luminescent material to form molecular excitons, and the amount of the electrons is increased. It is said that when the child excitons return to the ground state, they release energy and emit light. In addition, encouragement Singlet and triplet excitations are known as the excited states, and light emission is possible through either excited state. Is believed to be.

Recently, it has succeeded in lowering the drive voltage (see, for example, Patent Document 1). Metals with low work functions such as potash metals, alkaline earth metals, or rare earth metals (electron donating property) By doping the organic compound with the metal shown) to form an electron injection layer, from the cathode to the organic compound. It lowers the energy barrier in electron injection. Also, according to this method, the cathode The drive voltage can also be reduced by using a stable metal such as Al.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 10-270171</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2001-102175</text></patcit></p><p>Furthermore, by applying this technology, we have succeeded in controlling the emission spectrum of the light emitting element. (See, for example, Patent Document 2). Also in Patent Document 2, an electron is applied to an organic compound as an electron injection layer. It is doped with a metal that is child-friendly, but by increasing the film thickness of this layer, the cathode and light emitting layer Controls the emission spectrum emitted to the outside by the interference effect of light by changing the optical distance with It has been realized.</p><p>According to Patent Document 2, by applying the electron injection layer as described above, the emission spectrum can be obtained. Even if the film thickness of the electron injection layer is increased for control, the increase in drive voltage is said to be small. However, in reality, it is a special organic substance that functions as a ligand for vasocuproin (BCP) and the like. If no compound is used, the drive voltage will rise significantly.</p><p>That is, in the technique of the electron injection layer shown in Patent Documents 1 and 2, the film thickness is increased. , Control the emission spectrum to improve color purity, or improve yield Even so, unless an organic compound that functions as a ligand is selected, the drive voltage will rise and power consumption will increase. There was a problem that the power became large.</p><p> Here, with reference to FIG. 2, the operating principle of the light emitting element shown in Patent Document 1 and Patent Document 2 is used. explain.</p><p>FIG. 2 shows a conventional light emitting device using the electron injection layer described in Patent Documents 1 and 2 described above. This is the basic element structure.</p><p>In a conventional light emitting device (Fig. 2), when a forward bias is applied, holes injected from the anode 201 are injected. And the electrons injected from the cathode 204 are recombined in the layer 202 containing the luminescent material, leading to light emission. At this time, the electron injection layer 203 is formed of a metal (alkali metal or alkali) having a high electron donating property to the organic compound. It is a composition doped with potash earth metal).</p><p>The electron injection layer 203 has a role of causing electrons to flow and injecting electrons into the layer 202 containing a luminescent substance. Tsu. However, since the electron mobility of organic compounds is about two orders of magnitude smaller than the hole mobility, A film with a wavelength of visible light (submicron order) for the purpose of controlling the emission spectrum. If the thickness is increased, the drive voltage becomes high.</p>

<p>In view of the above problems, in the present invention, a product that functions as a ligand as in the prior art. The film thickness can be easily increased by a new means different from the light emitting element using quality, and the low drive voltage. It is an object of the present invention to provide a light emitting element capable of operating in the above. It also consumes less power, Moreover, it is an object of the present invention to provide a light emitting element having high color purity. At the same time, the power consumption is low An object of the present invention is to provide a light emitting element having a high yield.</p>

<p>As a result of diligent studies, the present inventor has provided a light emitting device having the following configuration. , Found that the problem can be solved.</p><p> In the present invention, between the anode and the cathode, a first layer containing a luminescent substance and a second layer containing an n-type semiconductor And a third layer containing a p-type semiconductor, the first layer with respect to the direction from the anode to the cathode. The first layer, the second layer, and the third layer are provided in order, and the third layer is provided in contact with the cathode. It is a light emitting element that has been struck.</p><p> Here, the n-type semiconductor is preferably a metal oxide, and in particular, zinc oxide, tin oxide, etc. And any one or more compounds selected from the group consisting of titanium oxide Is preferable. Further, the p-type semiconductor is preferably a metal oxide, and in particular, vanadium oxide. Selected from the group consisting of chromium, chromium oxide, molybdenum oxide, cobalt oxide, and nickel oxide It is preferably any one or more compounds that are exposed.</p><p> In the present invention, between the anode and the cathode, a first layer containing a luminescent substance, an organic compound and an electric child It has a second layer containing a substance exhibiting a property and a third layer containing a p-type semiconductor, and has an anode to a cathode. The first layer, the second layer, and the third layer are provided in order in the direction of, and the third layer is in contact with the cathode. It is a light emitting element provided so as to.</p><p>Here, the p-type semiconductor is preferably a metal oxide, and in particular, vanadium oxide and oxidation. Select from the group consisting of chromium, molybdenum oxide, cobalt oxide, and nickel oxide It is preferably a shift or one or more compounds. In addition, the organic compound in the second layer is It is preferably an organic compound exhibiting electron transportability, and in particular, has a ligand containing a π-conjugated skeleton. The metal complex to be used is preferable. In addition, the substance showing electron donating property is alkali metal or alkaline soil. It is preferably a metalloid or a rare earth metal.</p><p> In the present invention, between the anode and the cathode, a first layer containing a light emitting substance and a second layer containing an n-type semiconductor are included. It has a layer and a third layer containing an organic compound and a substance exhibiting electron acceptability, from an anode to a cathode. The first layer, the second layer, and the third layer are provided in order in the direction of, and the third layer is in contact with the cathode. It is a light emitting element provided so as to.</p><p>Here, the n-type semiconductor is preferably a metal oxide, and in particular, zinc oxide, tin oxide, and the like. And preferably any one or more compounds selected from the group consisting of titanium oxide. Good. Further, the organic compound in the third layer is preferably a hole-transporting organic compound. In particular, it is preferably an organic compound having an aromatic amine skeleton. Also, electron acceptability The substance shown is preferably a metal oxide.</p><p>In the present invention, between the anode and the cathode, a first layer containing a luminescent substance, a first organic compound and electricity A second layer containing a child-friendly substance and a second organic compound and a substance exhibiting electron acceptability. It has a third layer, including, with respect to the direction from the anode to the cathode, the first layer, the second layer and the third layer. Are in order, and the third layer is a light emitting element provided so as to be in contact with the cathode.</p><p>Here, the first organic compound is preferably an organic compound exhibiting electron transportability, and in particular, It is preferably a metal complex having a ligand containing a π-conjugated skeleton. It also shows electron donation. The substance is preferably an alkali metal or an alkaline earth metal or a rare earth metal. .. Further, the second organic compound is preferably a hole-transporting organic compound, and is particularly good. It is preferably an organic compound having an aromatic amine skeleton. In addition, substances that exhibit electron acceptability Is preferably a metal oxide.</p><p> In the present invention, a first layer containing a luminescent substance and an organic compound and a metal are provided between the anode and the cathode. It has a second layer containing and a third layer made of a metal oxide, with respect to the direction from the anode to the cathode. The first layer, the second layer, and the third layer are provided in order, and the third layer is provided so as to be in contact with the cathode. It is a light emitting element. Alternatively, a first layer containing a luminescent material between the anode and the cathode And the second layer containing organic compounds and metals, and the organic compounds contained in the second layer are different. It has a third layer containing machine compounds and metal oxides, and has a first layer with respect to the direction from the anode to the cathode. Layer, second layer and third layer are provided in order, and the third layer is provided so as to be in contact with the cathode. It is a light emitting element.</p><p>Here, it is preferable that the organic compound contained in the second layer is an electron-transporting organic compound. In particular, it is preferably a metal complex having a ligand containing a π-conjugated skeleton. Also, the third The second organic compound contained in the layer is preferably a hole-transporting organic compound, particularly aromatic. It is preferably an organic compound having an amine skeleton. Also, the metal is an alkali metal Is preferably an alkaline earth metal or a rare earth metal. In addition, metal oxides are oxidized. Consists of vanadium, chromium oxide, molybdenum oxide, cobalt oxide, and nickel oxide It is preferably any one or more compounds selected from the group.</p><p>In the light emitting device of the present invention, even when the sputtering method is used to form the cathode, It is possible to obtain a light emitting element that exhibits good characteristics with little damage to the light emitting element due to sputtering. Wear. For this reason, indium tin oxide (ITO) formed mainly by the sputtering method Shape the cathode using a conductor that can transmit visible light, such as: indium Tin Oxide) Can be done. Such a transparent electrode made of a conductive material capable of transmitting visible light was used. In this case, it is possible to obtain a light emitting element capable of extracting light emission from the cathode side as well.</p>

<p>According to the present invention, a light emitting device using a substance that functions as a ligand as in the prior art. Is a light emitting element that can be easily thickened by different new means and can operate at a low drive voltage. Can be obtained. As a result, the light emitting element has low power consumption and high color purity. Can be obtained. At the same time, a light emitting element with low power consumption and high yield Obtainable.</p><p>Furthermore, by manufacturing a light emitting device using the light emitting element, the color purity is high and the yield is also high. It is possible to provide a light emitting device that is good and has low power consumption.</p>

<figref num="1">The figure explaining the element structure of the light emitting element of this invention.</figref><figref num="2">The figure explaining the element structure of the conventional light emitting element.</figref><figref num="3">The figure explaining the element structure of the light emitting element of this invention.</figref><figref num="4">The figure explaining the element structure of the light emitting element of this invention.</figref><figref num="5">The figure explaining the light emitting device.</figref><figref num="6">The figure explaining the element structure of the light emitting element of this invention.</figref><figref num="7">The figure explaining the element structure of the comparative example with respect to the light emitting element of this invention.</figref><figref num="8">The figure explaining the element structure of the comparative example with respect to the light emitting element of this invention.</figref><figref num="9">The figure explaining the light emitting device.</figref><figref num="10">The figure explaining the electric appliance.</figref><figref num="11">The figure which shows the voltage-luminance characteristic of a light emitting element.</figref><figref num="12">The figure which shows the current-voltage characteristic of a light emitting element.</figref><figref num="13">The figure which shows the emission spectrum of a light emitting element.</figref><figref num="14">The figure explaining the element structure of the light emitting element of this invention.</figref><figref num="15">The figure explaining the element structure of the comparative example with respect to the light emitting element of this invention.</figref><figref num="16">The figure which shows the emission spectrum of a light emitting element.</figref><figref num="17">The figure which shows the emission spectrum of a light emitting element.</figref>

Hereinafter, embodiments of the present invention will be described in detail with reference to operating principles and specific configuration examples. I will reveal.

First, the operating principle of the light emitting device of the present invention will be described with reference to FIG. FIG. 1 shows the origin of the present invention. This is the basic element structure of an optical element.

In the light emitting device of the present invention (FIG. 1), the first layer 102 and the first layer 102 are located between the anode 101 and the cathode 105. The second layer 103 and the third layer 104 are provided in order from the anode 101 to the cathode 105. It has a well-established structure. The anode in the present invention is an electrode for injecting holes. As expected. Further, the cathode in the present invention may act as an electrode for injecting electrons, or may act as an electrode. It may act as an electrode to receive the fuel.

The second layer 103 is a layer that generates electrons and transports electrons, and is an n-type semiconductor or a layer thereof. Mixture containing, or a mixture of an organic compound having a carrier transport property and a substance having a high electron donating property It consists of things. The third layer 104 is a layer that generates holes and transports holes, and is p-type. Semiconductors or mixtures containing them, or organic compounds with carrier transport properties and electron acceptability Consists of a mixture with high substances. Further, the first layer 102 is a layer containing a luminescent substance, and is a layer containing a luminescent substance. It consists of a single layer or multiple layers.

The first layer 102, the second layer 103, and the third layer 104 originate in the first layer 102. The film thickness of each layer and the substances that make up each layer are selected and laminated so that an optical region is formed. To.

When a forward bias is applied to the light emitting device having such a configuration, as shown in FIG. 1, the second layer 103 Electrons and holes flow out in opposite directions from the vicinity of the interface between and the third layer 104. like this Of the carriers generated in the above, the electrons recombine with the holes injected from the anode 101 and Light emission occurs in the first layer 102. On the other hand, the holes escape toward the cathode 105 as they are. It becomes. At this time, focusing on the second layer 103 and the third layer 104, the pn junction is paired. In the state where the reverse bias is applied, the amount of carriers generated is remarkably large. Although not, it is sufficient to drive the light emitting element.

As described above, the light emitting device of the present invention can generate holes and move the holes. The optical distance can be adjusted by increasing the film thickness of the third layer. In this respect, electricity including BCP Light by increasing the film thickness of the child injection layer 203, that is, the layer that generates electrons and transports the electrons. It is different from the conventional light emitting element (Fig. 2) that adjusts the academic distance.

Normally, the hole mobility of organic compounds used as hole transport materials is the same as that of electron transport materials. The mobility is higher than the electron mobility of the organic compounds used in the above. Therefore, according to the present invention By thickening the layer that can move holes (third layer), the optical distance can be increased. By adjusting, the increase in drive voltage due to the increase in film thickness can be suppressed.

Hereinafter, one aspect of the present invention will be described with reference to the drawings. However, the present invention has many differences. It is possible to carry out in such a manner, and without departing from the gist of the present invention and its scope. It is easily understood by those skilled in the art that the form and details can be changed in various ways. Therefore, The interpretation is not limited to the description of the present embodiment.

(Embodiment 1) In the first embodiment, the light emitting device of the present invention will be described with reference to FIG.

In FIG. 3, the anode 301 is formed on the substrate 300, and the light emitting substance is contained on the anode 301. One layer 302 is formed, a second layer 303 is formed on the first layer 302, and a second layer 30 It has a structure in which a third layer 304 is formed on the third layer and a cathode 305 is formed on the third layer 304.

The material used for the substrate 300 here is that of a conventional light emitting element. It suffices, for example, from glass, quartz, transparent plastic, flexible substrates, etc. Can be used.

As an anode material that can be used as an anode 301, it has a large work function (work function 4). .0eV and above) Use metals, alloys, electrically conductive compounds, and mixtures thereof. Is preferable. As a specific example of the anode material, ITO (indium tin oxi) de), ITO containing silicon, 2 to 20 [%] zinc oxide (ZnO) in indium oxide In addition to IZO (indium zinc oxide) mixed with gold (Au) and platinum (P) t), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), Nitrogen of iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or metallic materials A compound (TiN) or the like can be used.

On the other hand, as the cathode material used for forming the cathode 305, the work function is small (work function 3). .8eV or less) Use metals, alloys, electrically conductive compounds, and mixtures thereof. Is preferable. As a specific example of the cathode material, an element belonging to Group 1 or Group 2 of the Periodic Table of the Elements Element, that is, alkali metals such as Li and Cs, and alkaline earth gold such as Mg, Ca and Sr. Genus and alloys (Mg: Ag, Al: Li) and compounds (LiF, CsF, C) containing these aF₂) And transition metals including rare earth metals can be used, but Al and Ag , ITO and the like can also be formed by laminating with a metal (including an alloy).

The above-mentioned anode material and cathode material form a thin film by a vapor deposition method, a sputtering method, or the like. By doing so, the anode 301 and the cathode 305 are formed, respectively. The film thickness is 10 to 500 It is preferably nm. Finally, inorganic materials such as SiN, Teflon (registered trademark), and styrene A protective layer (barrier layer) made of an organic material such as a polymer may be formed. The barrier layer is transparent It may be opaque or opaque, and the above-mentioned inorganic material or organic material may be vapor-deposited or spattered. It is formed by the ang method.

Furthermore, in order to prevent oxidation and moisture of the organic layer and electrodes of the light emitting element, dry SrOx, SiOx, etc. Even if the desiccant is formed by electron beam irradiation method, vapor deposition method, sputtering method, sol-gel method, etc. Good.

Further, in the light emitting device of the present invention, the carrier in the layer containing the light emitting substance, which is the first layer, The light generated by the recombination is either the anode 301 or the cathode 305, as shown in FIG. Is configured to be emitted to the outside from both (the arrow in the figure is the light emitting direction). That is, the sun When emitting light from the pole 301 (Fig. 3 (A)), the anode 301 is made of a translucent material. When light is emitted from the cathode 305 side (Fig. 3 (B)), the cathode 305 is used. It is made of a translucent material, and light is emitted from both sides of the anode 301 and the cathode 305. In this case (Fig. 3 (C)), the anode 301 and the cathode 305 are made of a translucent material.

Further, the first layer 302 is formed by laminating a plurality of layers, but in the first embodiment, the first layer 302 is formed. Is formed by laminating the fourth layer 311, the fifth layer 312, and the sixth layer 313. .. The fourth layer 311 is a hole injection layer containing a hole injection material, and the fifth layer 312 is positive. A hole transport layer containing a hole transport material. The sixth layer 313 contains a luminescent material and applies an electric field. It is a light emitting layer in which a light emitting region is formed when the light emitting region is formed.

Further, a known material can be used for the first layer containing a luminescent substance, which is a low molecular weight material. Either a material or a polymer-based material can be used.

A phthalocyanine compound is effective as a hole-injecting material that forms the fourth layer 311. is there. For example, phthalocyanine (abbreviation: H)₂-Pc), copper phthalocyanine (abbreviation: abbreviation: Cu-Pc) etc. can be used.

The hole-transporting material forming the fifth layer 312 is an aromatic amine-based material (ie, benze). A compound having a carbon-nitrogen bond) is suitable. As a widely used material , For example, 4,4'-bis [N- (3-methylphenyl) -N-phenyl-amino] -bi In addition to phenyl (abbreviation: TPD), its derivative 4,4'-bis [N- (1-naphthyl) )-N-Phenyl-Amino] -Biphenyl (abbreviation: α-NPD), or 4,4', 4 ''-Tris (N, N-diphenyl-amino) -triphenylamine (abbreviation: TDATA) ), 4,4', 4''-Tris [N- (3-Methylphenyl) -N-Phenyl-Amino] -Starburst aromatic amine compounds such as triphenylamine (abbreviation: MTDATA) Things can be mentioned. In addition, a conductive inorganic compound such as molybdenum oxide is used alone, or the above-mentioned organic compound is used. A composite material mixed with an object can also be used.

Examples of the luminescent substance contained in the sixth layer 313 include quinacridone, coumarin, and ruble. , Styryl dye, tetraphenyl butadiene, anthracene, perylene, coronene, In addition to organic compounds such as 12-phthaloperinone derivatives, tris (8-quinolinolato) aluminum Nium (hereinafter Alq₃) And other metal complexes can be mentioned.

The second layer 303 is zinc oxide, tin oxide, titanium oxide, zinc sulfide, zinc selenide, tellurized. Whether it is composed of n-type semiconductors such as zinc or contains these n-type semiconductors. Just do it. Alternatively, even if the organic compound is doped with a substance exhibiting electron donating property. Good. As the organic compound at this time, an electron transporting material is preferable, and 2- (4-biphenylyl) ) -5- (4-tert-Butylphenyl) -1,3,4-oxadiazole (abbreviation: P) BD) and OXD-7, TAZ, p-EtTAZ, BPhen, BCP mentioned above. In addition to this, Alq, which has conventionally seen an increase in drive voltage₃, Tris (5-methyl-8-ki Norinorat) Aluminum (abbreviation: Almq)₃), Bis (10-hydroxybenzo [h] -Kinorinato) Beryllium Abbreviation: BeBq₂) Such as quinoline skeleton or benzoquinoline Metal complexes with a skeleton and bis (2-methyl-8-quinolinolato) -4-phenylpheno Rat-aluminum (abbreviation: BAlq) can be mentioned. On the other hand, as a substance that exhibits electron donating property Alkali metals such as Li and Cs, and alkaline earth metals such as Mg, Ca and Sr. Or rare earth metals such as Er and Yb. Besides this, for example Alq₃Against electric children It is an organic compound such as tetrathiafulvalene or tetramethylthiafulvalene that exhibits giving properties. You may.

The third layer 304 contains vanadium oxide, chromium oxide, molybdenum oxide, cobalt oxide, and oxidation. A configuration consisting of p-type semiconductors such as nickel, or a configuration including those p-type semiconductors. All you need is. Alternatively, the organic compound is doped with a substance exhibiting electron acceptability. You may. As the organic compound at this time, a hole-transporting material is preferable, and an aromatic amine-based material is formed. A mixture is suitable. For example, in addition to TPD, its derivative α-NPD or TDA Examples include starburst aromatic amine compounds such as TA and MTDATA. On the other hand, electricity Examples of substances showing child acceptability include molybdenum oxide, which shows electron acceptability for α-NPD. Examples include metal oxides such as vanadium oxide and vanadium oxide. In addition, it receives electrons for α-NPD. Tolerant tetracyanoquinodimethane (abbreviation: TCNQ) and 2,3-dicyanonaphthoquino It may be an organic compound such as (abbreviation: DCNNQ).

From the above, the light emitting element of the present invention can be formed. In this embodiment, it is shown in the figure. Although not, a material with excellent electron transportability so that a part of the first layer 302 is in contact with the second layer 303. The structure may be provided with a layer made of a material. Specific examples of materials with excellent electron transportability include For example, Tris (8-quinolinolato) aluminum (abbreviation: Alq)₃), Tris (5-methyl) -8-Kinorinorat) Aluminum (abbreviation: Almq)₃), Bis (10-Hydroxyben Zo [h]-Kinorinato) Beryllium (abbreviation: BeBq)₂), Bis (2-methyl-8-quino) Quinoline, such as linolato) -4-phenylphenolato-aluminum (abbreviation: BAlq) A layer composed of a skeleton or a metal complex having a benzoquinoline skeleton. In addition, other screws [2- (2-Hydroxyphenyl) -benzoxazolate] Zinc (abbreviation: Zn (BOX))₂), Bis [2- (2-Hydroxyphenyl) -benzothiazolato] Zinc (abbreviation: Zn (abbreviation: Zn ( BTZ)₂) And other oxazole-based and thiazole-based ligand-bearing metal complexes are also used. be able to. In addition to metal complexes, 2- (4-biphenylyl) -5- (4-te rt-Butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD) and 1,3- Bis [5- (p-tert-butylphenyl) -1,3,4-oxadiazole-2-a Le] Benzene (abbreviation: OXD-7), 3- (4-tert-butylphenyl) -4-phenyl Nil-5- (4-biphenylyl) -1,2,4-triazole (abbreviation: TAZ), 3-( 4-tert-Butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenyli) Le) -1,2,4-triazole (abbreviation: p-EtTAZ), basophenanthroline (abbreviation) Name: BPhen), Basocuproin (abbreviation: BCP), etc. can also be used.

In the above-mentioned light emitting device of the present invention, when the cathode is formed of a conductive material that transmits visible light, the figure is shown in the figure. As shown in 3 (B), light emission can be taken out from the cathode side. In addition, it is a guide that transmits visible light. When the anode is formed of electrical material, light emission can be extracted from the anode side as shown in Fig. 3 (A). To. Furthermore, when both the cathode and the anode are made of a conductive material that transmits visible light, Fig. 3 ( As shown in C), light emission can be taken out from both sides.

As a conductor that can transmit visible light and has relatively high conductivity, as described above, I Examples include TO and IZO. Due to their high work function, these are usually the materials that form the cathode. Is unsuitable for.

However, in the light emitting device of the present invention, a layer and an electron that generate holes and transport holes are generated. Work like ITO and IZO by having a layer that transports electrons Even if a material with a high function is used, the drive voltage does not increase. Therefore, in the light emitting device of the present invention Can use ITO, IZO, or the like as a material for forming a cathode.

Further, in the light emitting device of the present invention, it is the case where the sputtering method is used for forming the cathode. However, it is possible to obtain a light emitting element that exhibits good characteristics with little damage to the light emitting element due to sputtering. Can be done. This allows visible light such as ITO, which is mainly formed by the sputtering method, to pass through. It is advantageous when forming a cathode using a conductor that can be passed.

(Embodiment 2) In the second embodiment, the configuration of the light emitting device of the present invention will be described with reference to FIG.

The substrate 400, the anode 401, the first layer 402, the second layer 403, the third layer 404, and the shade. The pole 405 can be formed in the same manner using the same material as in the first embodiment. The explanation is omitted because it can be done.

Further, in FIG. 4, the cathode 405 is formed on the substrate 400, and the third layer 404 is formed on the cathode 405. Is formed, a second layer 403 is formed on the third layer 404, and a luminescent material is formed on the second layer 403. It has a structure in which a first layer 402 containing a quality is formed, and an anode 401 is formed on the first layer 402.

Further, in the light emitting device of the present invention, the carrier in the layer containing the light emitting substance, which is the first layer, The light generated by the recombination goes out from one or both of the anode 401 and the cathode 405. It will be shot. That is, when light is emitted from the anode 401 (Fig. 4 (A)) , When the anode 401 is made of a translucent material and light is emitted from the cathode 405 side. (Fig. 4 (B)) shows that the cathode 405 is made of a translucent material, and the anode 401 and When light is emitted from both sides of the cathode 405 (Fig. 4 (C)), the anode 401 and the cathode 405 Is made of a translucent material.

From the above, the light emitting device of the present invention can be manufactured.

In the above-mentioned light emitting device of the present invention, when the anode is formed of a conductive material that transmits visible light, the figure is shown in the figure. As shown in 4 (A), light emission can be taken out from the anode side. In addition, it is a guide that transmits visible light. When the cathode is formed of electrical material, light emission can be extracted from the cathode side as shown in Fig. 4 (B). To. Furthermore, when both the cathode and the anode are made of a conductive material that transmits visible light, Fig. 4 ( As shown in C), light emission can be taken out from both sides.

As described in the second embodiment, the conductor can transmit visible light and has relatively high conductivity. Examples of electrical materials include ITO, IZO, and the like as described above. These are work functions Therefore, it is usually unsuitable as a material for forming a cathode.

However, in the light emitting device of the present invention, a layer and an electron that generate holes and transport holes are generated. Work like ITO and IZO by having a layer that transports electrons Even if a material with a high function is used, the drive voltage does not increase. Therefore, in the light emitting device of the present invention Can use ITO, IZO, or the like as a material for forming a cathode.

(Embodiment 3) In this embodiment, glass, quartz, metal, bulk semiconductor, transparent plastic, flexible A light emitting element is manufactured on a substrate 500 made of a sex substrate or the like. Such light emission on one board By manufacturing a plurality of elements, a passive type light emitting device can be manufactured. Also, gala In addition to substrates made of silica, quartz, transparent plastic, flexible substrates, etc., for example, Fig. 5 shows. As described above, a light emitting device in contact with a thin film transistor (TFT) array may be manufactured. here , 511 and 512 are used as TFTs, and 513 is used as the light emitting device of the present invention. Light emitting element 513 is positive The pole 514, the first layer, the second layer and the third layer consist of 515 and the cathode 516, wiring 5 It is electrically connected to the TFT 511 via 17. This causes the TFT to emit light. An active matrix type light emitting device that controls the drive of an element can be manufactured. In addition, of TFT The structure is not particularly limited. For example, it may be a staggered type or an inverted staggered type. Also T The crystallinity of the semiconductor layer constituting the FT is not particularly limited, and may be crystalline. It may be amorphous.

<p>In this embodiment, one aspect of the light emitting device of the present invention will be specifically exemplified. Figure 6 shows the element structure It will be described using.</p><p>First, the anode 601 of the light emitting element is formed on the substrate 600. Transparent conductive film as a material It was formed with a film thickness of 110 nm by a sputtering method using ITO. Shape of anode 601 Was 2 mm square.</p><p>Next, a first layer 602 containing a luminescent material is formed on the anode 601. In addition, in this embodiment The first layer 602 containing the luminescent material is composed of three layers, namely the hole injection layer 611 and the hole transport. It has a laminated structure composed of a layer 612 and a light emitting layer 613.</p><p>First, the anode 601 is formed on the substrate holder of the vacuum vapor deposition apparatus on the substrate on which the anode 601 is formed. Copper phthalocyanine is fixed to the evaporation source provided inside the vacuum vapor deposition equipment with the surface facing down. (Hereinafter referred to as Cu-Pc) is added and the film thickness is 20 nm by the vapor deposition method using the resistance heating method. A hole injection layer 611 was formed. As a material for forming 611, a known hole injectability Materials can be used.</p><p>Next, the hole transport layer 612 is formed from a material having excellent hole transport properties. Material forming 612 A known hole-transporting material can be used as the agent, but in this example, α-NPD Was formed with a film thickness of 40 nm by the same method.</p><p>Next, the light emitting layer 613 is formed. A known luminescent substance is used as the material for forming 613. However, in this example, Alq₃Is formed with a film thickness of 40 nm by the same method. did. Here, Alq₃Acts as a luminescent substance.</p><p>In this way, after the three layers 611, 612, 613 are laminated and formed, the second layer 6 03 is formed. In this embodiment, Alq is used as an electron transporting material.₃, Alq₃Against electricity Using Mg as a child-friendly substance, the second layer 603 by the co-evaporation method with a film thickness of 30 nm. Was formed. The proportion of Mg was 1 wt%.</p><p>Next, a third layer 604 is formed. In this example, α-NPD is used as the hole transporting material. , Using molybdenum oxide as a substance that exhibits electron acceptability to α-NPD, 150 nm A third layer was formed by the co-deposition method based on the film thickness. The ratio of molybdenum oxide was 25 wt%. As a raw material for molybdenum oxide, molybdenum oxide (VI) was used.</p><p>Next, the cathode 605 is formed by a sputtering method or a vapor deposition method. In this embodiment, , By forming aluminum (150 nm) on the third layer 604 by thin film deposition Obtained pole 605.</p><p>As described above, the light emitting device of the present invention was formed. Figure 1 shows the brightness-voltage characteristics of the obtained device. Fig. 12 shows the current-voltage characteristics, and Fig. 13 shows the emission spectrum when a current of 1 mA is applied. Show each.</p><p>When a voltage is applied to the formed light emitting element, the light emission start voltage (here, the brightness is 1 cd / m).²The voltage at that time was 6.0V. In addition, the brightness when 1mA of current is passed is 1130c. d / m²Met. The CIE chromaticity coordinates at this time are (X, Y) = (0.29,0.63). ), And it was green with good color purity.</p><p>(Comparative example 1) In Comparative Example 1, the second layer and the third layer of the present invention were not used, and instead the electron injection layer 703 was used. A specific example will be given of a conventional light emitting device provided with the above. The element structure will be described with reference to FIG. The electron injecting layer 703 is the electron transporting material Alq as in the second layer 603 of Example 1.₃A configuration in which 1% of Mg, which is a substance exhibiting electron donating property, was doped was applied to. Electron injection layer 70 The film thickness of 3 was set to 30 nm as in the second layer in Example 1. Also, another board 700 , Anode 701, hole injection layer 711, hole transport layer 712, and light emitting layer 713. The layers 702 and the cathode 704 including the same structure were all the same as in Example 1. Therefore, Example 1 Compared with this Comparative Example 1, the film thickness (150 nm) of the third layer 604 is thicker.</p><p>The brightness-voltage characteristics of the obtained device are shown in Fig. 11, the current-voltage characteristics are shown in Fig. 12, and the current flows by 1 mA. The emission spectra at the time of each are shown in FIG. Apply voltage to the formed light emitting element The emission start voltage was 5.4V. In addition, the brightness when 1mA of current is passed is 1360c. d / m²Met. The CIE chromaticity coordinates at this time are (X, Y) = (0.34,0.58). ), And it was yellowish green with poor color purity.</p><p>From the above results, Example 1 of the present invention has a total film thickness of 150 nm as compared with Comparative Example 1. Despite its thickness, its drive voltage (6.0V) is almost different from that of Comparative Example 1 (5.4V). I found that I didn't understand. Moreover, when comparing the emission spectra in FIG. 13, the ratio of Example 1 is found. The spectrum width is narrower than that of the emission spectrum of Comparative Example 1, which leads to an improvement in color purity. It is thought that</p><p>(Comparative example 2) In this Comparative Example 2, the substrate 800, the anode 801 and the hole injection layer 811 and the hole transport layer 812 and light emission The layer 802 and the cathode 804 containing the luminescent substance composed of the layer 813 all have the same configuration as in Example 1. , A conventional light emitting device provided with the electron injection layer 803 will be specifically illustrated. Figure 8 of the element structure Will be described with reference to. Here, the configuration of the electron injection layer 803 is the same as that of Comparative Example 1, but the film thickness. The total film thickness was set to 180 nm so that the total film thickness was the same as that of Example 1.</p><p>The brightness-voltage characteristics of the obtained device are shown in Fig. 11, the current-voltage characteristics are shown in Fig. 12, and the current flows by 1 mA. The emission spectra at the time of each are shown in FIG. Apply voltage to the formed light emitting element The emission start voltage was 14.0V. Also, the brightness when 1mA of current is passed is 1050. cd / m²Met. The CIE chromaticity coordinates at this time are (X, Y) = (0.25,0.6). It was 3), and it was green with good color purity.</p><p>From the above results, in the configuration of Comparative Example 2, as can be seen from FIG. 13, the spectrum width is narrow. Although the color purity is good, the drive voltage is significantly increased as compared with Example 1 of the present invention, which has the same film thickness. You can see that it has been done.</p><p>Therefore, between the pair of electrodes (anode 601 and cathode 605), the first layer 602 and the second By implementing the configuration of the present invention in which the layer 603 and the third layer 604 are provided in order, the film thickness is increased. The color purity can be improved by increasing the thickness, and at the same time, the drive voltage can be improved even if the film thickness is increased. It was found that the rise of the</p>

<p>In the second embodiment, one aspect of the light emitting device of the present invention will be specifically exemplified. Figure 1 of the element structure This will be explained using 4.</p><p>First, the anode 2401 of the light emitting element is formed on the substrate 2400. With transparent conductive film as a material It was formed with a film thickness of 110 nm by a sputtering method using a certain ITO. Anode 2401 The shape of is 2 mm square.</p><p>Next, a first layer 2402 containing a luminescent material is formed on the anode 2401. In addition, this Example The first layer 2402 containing the luminescent material in the three layers, namely the hole injection layer 2411, It has a laminated structure consisting of a hole transport layer 2412 and a light emitting layer 2413.</p><p>First, the anode 2401 is formed on the substrate holder of the vacuum vapor deposition apparatus on which the anode 2401 is formed. Fix the formed surface downward, and put Cu-Pc in the evaporation source provided inside the vacuum deposition apparatus. The hole injection layer 2411 was formed with a film thickness of 20 nm by a thin-film deposition method using a resistance heating method. .. A known hole-injectable material can be used as the material for forming 2411. ..</p><p>Next, the hole transport layer 2412 is formed from a material having excellent hole transport properties. Form 2412 A known hole transporting material can be used as the material, but in this example, α-N It was formed with a film thickness of 40 nm by the same method using PD.</p><p>Next, the light emitting layer 2413 is formed. Although known luminescent substances can be used for 2413, , In this example, Alq₃And by co-depositing coumarin 6 with Alq₃And bear A layer composed of phosphorus 6 was formed with a film thickness of 40 nm. Here, coumarin 6 is used as a luminescent substance. It works. In the case of co-deposition, Alq₃And the mass ratio of coumarin 6 is Alq₃: Coumarin It was adjusted so that 6 = 1: 0.003.</p><p>In this way, after the three layers 2411, 2412, and 2413 are laminated and formed, the second Layer 2403 is formed. In this embodiment, Alq is used as an electron transporting material.₃, Alq₃To On the other hand, Li is used as a substance showing electron donating property, and the second is by co-depositing method with a film thickness of 30 nm. Layer 2403 was formed. The ratio of Li was 1 wt%.</p><p>Next, a third layer 2404 is formed. In this example, α-NPD is used as the hole transporting material. Using molybdenum oxide as a substance that exhibits electron acceptability to α-NPD, 180 nm A third layer 2404 was formed by the co-evaporation method at the film thickness of. Molybdenum oxide ratio is 25wt %. As a raw material for molybdenum oxide, molybdenum oxide (VI) was used.</p><p>Next, the cathode 2405 is formed by a sputtering method or a vapor deposition method. In addition, in this embodiment By forming aluminum (200 nm) on the third layer 2404 by thin film deposition. A cathode 2405 was obtained.</p><p>When a voltage is applied to the light emitting element formed as described above, the light emission start voltage (here, brightness) is applied. Degree is 1 cd / m²The voltage at that time was 3.4V. Also, when 1mA of current is applied Brightness is 2700 cd / m²The emission spectrum has a sharp shape as shown in FIG. showed that. The CIE chromaticity coordinates at this time are (X, Y) = (0.21,0.69). The color was green with extremely good color purity.</p><p>(Comparative example 3) In Comparative Example 3, the second layer and the third layer of the present invention were not used, and instead, the electron injection layer 250 was used. A conventional light emitting device provided with 3 will be described with reference to FIG. As electron injection layer 2503 Is the same as the second layer 2403 of Example 2, the electron transporting material Alq.₃Shows electron donation A configuration in which the substance Li was doped with 1 wt% was applied. The film thickness of the electron injection layer 2503 is actually As with the second layer in Example 2, it was set to 30 nm. Also, other substrates 2500, anode 250 1. Contains a luminescent substance consisting of a hole injection layer 2511, a hole transport layer 2512, and a light emitting layer 2513. The layer 2502 and the cathode 2504 all had the same configuration as in Example 2. Therefore, Example 2 Compared with this Comparative Example 3, the film thickness (180 nm) of the third layer 2404 is thicker.</p><p>When a voltage was applied to the obtained element of Comparative Example 3, the emission start voltage was 3.2V. Also , The brightness when 1mA of current is passed is 3300cd / m²However, the emission spectrum is shown in Fig. 1. As shown in 6, it showed a broad shape. The CIE chromaticity coordinates at this time are (X, Y) = It was (0.30,0.64), and the color purity was not very good green.</p><p>From the above results, Example 2 of the present invention has a total film thickness of 180 nm as compared with Comparative Example 3. Despite its thickness, its drive voltage (3.4V) is almost different from that of Comparative Example 3 (3.2V). I found that I didn't understand. Further, comparing the emission spectra in FIG. 16, Example 2 is a book. The spectrum width is narrower than the emission spectrum of Comparative Example 3, which leads to an improvement in color purity. It is thought that it is.</p>

<p>In Example 3, one aspect of the light emitting device of the present invention will be illustrated. The element structure is shown in Fig. 14. I will explain. In this Example 3, it was formed in the same manner as in Example 2 except for the third layer 2404. The third layer 2404 is formed by depositing only molybdenum oxide at 260 nm. Ta. As the raw material for molybdenum oxide, molybdenum oxide (VI) was used.</p><p>When a voltage is applied to the light emitting element formed as described above, the light emission start voltage (here, brightness) is applied. Degree is 1 cd / m²The voltage at that time was 4.6V. Also, when 1mA of current is applied Brightness is 2800 cd / m²And the emission spectrum has a sharp shape as shown in FIG. showed that. The CIE chromaticity coordinates at this time are (X, Y) = (0.23, 0.71). The color was green with extremely good color purity. For comparison, the emission spec of Comparative Example 3 described above The toll was also placed in Fig. 17.</p><p>From the above results, Example 3 of the present invention has a total film thickness of 260 nm as compared with Comparative Example 3. Nevertheless, its drive voltage (4.6V) is significantly higher than that of Comparative Example 3 (3.2V). No rise was seen. Further, comparing the emission spectra in FIG. 17, Example 3 is a comparative example. The spectrum width is narrower than the emission spectrum of 3, which leads to the improvement of color purity. It is thought that.</p>

<p>In this embodiment, a light emitting device having the light emitting element of the present invention in the pixel portion will be described with reference to FIG. To. 9 (A) is a top view showing the light emitting device, and FIG. 9 (B) is FIG. 9 (A) in A-A'. It is a cut sectional view. 901 shown by the dotted line is the drive circuit section (source side drive circuit), 90 2 is a pixel unit, and 903 is a drive circuit unit (gate side drive circuit). In addition, 904 is a sealing substrate. , 905 is a sealant, and the inner 907 surrounded by the sealant 905 is a space. ..</p><p>In addition, 908 is a signal input to the source side drive circuit 901 and the gate side drive circuit 903. FPC (Flexible Print Circulation), which is the wiring for transmission and serves as an external input terminal. G) Receive video signal, clock signal, start signal, reset signal, etc. from 909. Although only the FPC is shown here, this FPC has a printed wiring board (PW). B) may be attached. The light emitting device in the present specification includes only the light emitting device main body. It does not include the state where the FPC or PWB is attached to it.</p><p>Next, the cross-sectional structure will be described with reference to FIG. 9 (B). On the board 910, the drive circuit section and The pixel part is formed, but here, the source side drive circuit 901, which is the drive circuit part, and the image The element part 902 is shown.</p><p>The source side drive circuit 901 is an n-channel type TFT923 and a p-channel type TFT924. A CMOS circuit is formed by combining with. Further, the TFT forming the drive circuit is known. It may be formed by a CMOS circuit, a MOSFET circuit or an NMOS circuit of. In addition, this embodiment Then, the driver integrated type in which the drive circuit is formed on the board is shown, but it is not always necessary. , It can also be formed on the outside instead of on the substrate.</p><p>In addition, the pixel unit 902 is a switching TFT911, a current control TFT912, and its drive. It is formed by a plurality of pixels including an anode 913 electrically connected to the rain. In addition, the sun An insulator 914 is formed over the end of the pole 913. Here, positive type photosensitive lye It is formed by using a lyl resin film.</p><p>Further, in order to improve the film forming property, the upper end portion or the lower end portion of the insulator 914 has a curvature. A curved surface is formed. For example, as a material for insulator 914, a positive photosensitive lye When Lil is used, only the upper end of the insulator 914 has a radius of curvature (0.2 μm to 3 μm). It is preferable to have a curved surface. Also, as an insulator 914, it can be squeezed by photosensitive light. Negative type that becomes insoluble in chant, or positive type that becomes soluble in chant by light Any of these can be used, and not only organic compounds but also inorganic compounds such as silicon oxide and acids can be used. Both silicon nitride, siloxane, etc. can be used.</p><p>First to third layers 916 and cathode 917 are formed on the anode 913, respectively. To. Here, as the material used for the anode 913, it is desired to use a material having a large work function. Good. For example, ITO (indium tin oxide) film, ITSO (indium tin) silicon oxide), indium zinc oxide (IZO) film, titanium nitride film, In addition to single-layer films such as chrome film, tungsten film, Zn film, and Pt film, titanium nitride and aluminium Lamination with a film containing aluminum as the main component, a titanium nitride film and a film containing aluminum as the main component, and titanium nitride A three-layer structure with a membrane can be used. In addition, if it is a laminated structure, resistance as wiring It is also low, good ohmic contact can be made, and it can function as an anode. ..</p><p>Further, the first to third layers 916 are formed by a thin-film deposition method using a thin-film deposition mask or an inkjet method. Formed by. The first to third layers 916 are the first layer containing a luminescent substance, n-type semiconducting material. It has a second layer containing a body and a third layer containing a p-type semiconductor, with respect to the direction from the anode to the cathode. , The first layer, the second layer, and the third layer are sequentially laminated, and the third layer is formed so as to be in contact with the cathode. Will be done. In addition, as a material used for a layer containing a luminescent substance, an organic compound is usually single-layered or laminated. Alternatively, it is often used in a mixed layer, but in the present invention, it is a part of a film made of an organic compound. A configuration using an inorganic compound is also included in the above.</p><p>Further, as a material used for the cathode 917 formed on the first to third layers 916, the work Materials with small functions (Al, Ag, Li, Ca, or alloys of these MgAg, MgIn, AlLi, CaF₂, Or CaN) may be used. In addition, in the first to third layers 916 When the generated light passes through the cathode 917, it is used as the cathode 917 and is made of a thin metal. Membrane, transparent conductive film ITO (indium tin oxide alloy), ITSO (indium t) in silicon oxide), indium zinc oxide alloy (In₂O₃ZnO ), Zinc oxide (ZnO), etc.) is recommended.</p><p>Furthermore, by bonding the sealing substrate 904 with the element substrate 910 with the sealing agent 905, the element is made. Light emitting element in space 907 surrounded by child substrate 910, sealing substrate 904, and sealant 905 It has a structure equipped with 918. In the space 907, an inert gas (nitrogen or al) is used. In addition to the case where Gon etc.) is filled, the configuration which is filled with the sealant 905 is also included.</p><p>It is preferable to use an epoxy resin for the sealant 905. Also, these materials It is desirable that the material is as impermeable to water and oxygen as possible. Also, on the sealing substrate 904 In addition to glass and quartz substrates, FRP (Fiberglass-Rein) is used as the material. forced Plastics), PVF (Polyvinyl Fluoride), Mylar, Poly A plastic substrate made of ester, acrylic or the like can be used.</p><p>As described above, a light emitting device having the light emitting element of the present invention can be obtained.</p><p>In the light emitting device shown in this embodiment, the configuration of the light emitting element shown in Examples 1 to 3 can be freely configured. It is possible to carry out in combination. Further, the light emitting device shown in this embodiment may be used as needed. A chromaticity conversion film such as a color filter may be used.</p>

<p>In this embodiment, various electric appliances completed by using the light emitting device having a light emitting element in the present invention. This will be described with reference to FIG.</p><p>As an electric appliance manufactured by using a light emitting device formed by using the present invention, a television, Video camera, digital camera, goggle type display (head mounted display) ), Navigation system, sound reproduction device (car audio, audio component, etc.), Notebook personal computers, game machines, personal digital assistants (mobile computers, An image playback device equipped with a mobile phone, a portable game machine, an electronic book, etc., and a recording medium (specifically) Is a table that can play a recording medium such as a digital video disc (DVD) and display the image. A device equipped with a display device) and the like. Specific examples of these electric appliances are shown in FIG.</p><p>Fig. 10 (A) shows the display device, which includes the housing 1001, the support base 1002, the display unit 1003, and the speed. -Includes car section 1004, video input terminal 1005, etc. Luminescent device formed using the present invention It is made by using the device for its display unit 1003. The display device is for personal computers. , TV broadcast reception, advertisement display, etc. All information display devices are included.</p><p>Figure 10 (B) shows a video camera, which is the main body 1301, the display 1302, the housing 1303, and the outside. Connection port 1304, remote control receiver 1305, image receiver 1306, battery 1307 , Voice input unit 1308, operation key 1309, eyepiece unit 1310, etc. Light emitting device of the present invention It is manufactured by using a light emitting device having the above for the display unit 1302.</p><p>Figure 10 (C) shows a mobile phone with a main unit 1501, a housing 1502, a display unit 1503, and voice input. Power unit 1504, audio output unit 1505, operation key 1506, external connection port 1507, Anne Includes Tena 1508 and others. A light emitting device having the light emitting element of the present invention is used for the display unit 1503. It is produced by.</p><p>As described above, the applicable range of the light emitting device having the light emitting element of the present invention is extremely wide, and the light emitting device is also used. Since the light emitting element used in the above is formed by using the light emitting element of the present invention, the driving voltage is low and the longevity is long. It has the characteristic of being a life. Therefore, this light emitting device is suitable for electric appliances in all fields. By using it, it is possible to realize low power consumption and long life.</p>